Google Images Re-Linker Frage

// All coding praise to biznatchio. I came up with this idea months ago, but could never
// get the damn thing to work. He looked at it twice and pumps out a flawless version
// of what I wanted in the first place. I'm leaving his comments in here so if people
// want to learn more about it, go right ahead, because I scoured the internet for
// a good way to do this and found jack and shit, respectively.

function checkURL(e) {
    
   // Since this function is called as an event handler, a DOM event object is passed
   // in as a parameter, which we take in as "e".  The event object contains an originalTarget
   // property, which tells us which object initiated the load event -- this will be the
   // HTMLDocument object that just finished loading.  By doing it this way and not using
   // window._content, the load events will be handled correctly if a page loads in a
   // background tab, since e.originalTarget will always point to the right document, whereas
   // window._content always points to the foreground tab.
   
   var doc = e.originalTarget;
   var loc = doc.location;
   try {
      if ( loc && loc.href ) {
         if ( loc.href.match( /^http:\/\/(images\.)?google\.(.*?)\//i ) ) {
            changeLinks(doc);
         }
      }
   }
   catch (ex) { }
}

function selectNodes(doc, context, xpath) {
   var nodes = doc.evaluate(xpath, context, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
   var result = new Array( nodes.snapshotLength );
   for (var x=0; x<result.length; x++) {
      result[x] = nodes.snapshotItem(x);
   }
   return result;
}

function changeLinks(doc) {
   // Get a list of all A tags that have an href attribute containing the start and stop key strings.
   var googLinks = selectNodes(doc, doc.body, "//A[contains(@href,'/imgres?imgurl=')][contains(@href,'&imgrefurl=')]");
      for (var x=0; x<googLinks.length; x++) {
      // Capture the stuff between the start and stop key strings.
      var gmatch = googLinks[x].href.match( /\/imgres\?imgurl\=(.*?)\&imgrefurl\=/ );
      // If it matched successfully...
      if (gmatch) {
         // Replace the link's href with the contents of the text captured in the regular expression's parenthesis.
         // The decodeURI fixed the special characters issue. (thanks Tivac)
         googLinks[x].href = decodeURI(gmatch[1]);
        }
   }
}

window.addEventListener('load', checkURL, true);